1. Field of the Invention
This invention relates in general to power sources, and in particular to pulse detonation engines such as for aircraft, missiles and rockets.
2. Description of the Prior Art
A pulse detonation engine is an apparatus which produces a high pressure exhaust from a series of repetitive detonations within a detonation chamber. The process is a constant volume heat addition process. A gaseous fuel is detonated within a chamber, causing a pulse detonation wave which propagates at supersonic speeds. The supersonic speeds approach or exceed Chapman Jouguet detonation velocities. This speed is to be distinguished from lower quality shock or deflagration expansion waves which travel supersonically at approximately one third of the Chapman Jouguet detonation velocities. The detonation wave compresses the fluid within the chamber, increasing its pressure, density and temperature. As the detonation wave passes out the open rearward end, thrust is created. The cycle is then repeated.
At high speeds, such as Mach 2 to about Mach 3.5, such an engine would be theoretically more efficient than conventional turbojets because the engine does not require compressors or turbines. A pulse detonation engine supplying the same amount or more of thrust as a conventional gas turbine engine would theoretically weigh less. Also, a pulse detonation engine could be used as a propulsion system for a rocket.
Another prior art engine, known as a pulse jet engine, was employed in World War II. That engine relied on slow moving deflagration, not detonation. The deflagration waves are subsonic, not supersonic waves. A pulse jet engine is not a pulse detonation engine.
Although theoretically desirable, to applicant's knowledge there are no pulse detonation engines being used as propulsion devices at this time. The reason may be the problems resulting from very high detonation chamber temperatures, approximately 3,500.degree. F. Also, initiating repetitive detonations is a problem. The detonation chamber must have an inlet port for supplying fuel, and the inlet port must close just before the detonation occurs. Very high pressures occur during the detonation. The valves must be capable of sealing against the high pressures under the high temperatures.